I love bridges.
Something about them. They're shweet.
I seriously think more bridge building contests should be about
architecture, not cost, even if that is a more real-life concern.
These are what I call "optimized", meaning that if any single member was thinner (that is, any less expensive), it would collapse.
The suspension bridge with exaggerated displacements enabled:
West Point Bridge Designer 2007 is free.
I don't think they're holding any more contests, but it's an awesome program, even if it's a tad out-dated looking.
You can get it here
Feel free to post your own fancy bridges.